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You've done the hard work already. Instead of calculating the product, store the selected array. <?php $primes = array(2, 3, 5, 7, 11, 13, 17, 19, 23); $combos = []; function getAllCombinations($arr, $n, &$combos, $selected = array(), $startIndex = 0) { if ($n == 0) { $combos[] = $selected; // $product = 1; // foreach ($selected as $prime) { // $pr[] = $prime; // $product *= $prime; // $pr[] = $prime; // } // echo "Product: $product\n"; return; } for ($i = $startIndex; $i < count($arr); $i++) { $selected[] = $arr[$i]; getAllCombinations($arr, $n - 1, $combos, $selected, $i + 1); array_pop($selected); // Backtrack and remove the element for next iteration } } getAllCombinations($primes, 4, $combos); echo '<pre>'; foreach ($combos as $com) { printf("%-35s = %5d<br>", join(' &times; ', $com), array_product($com)); // output numbers and product } ?> giving 2 × 3 × 5 × 7 = 210 2 × 3 × 5 × 11 = 330 2 × 3 × 5 × 13 = 390 2 × 3 × 5 × 17 = 510 2 × 3 × 5 × 19 = 570 2 × 3 × 5 × 23 = 690 2 × 3 × 7 × 11 = 462 2 × 3 × 7 × 13 = 546 2 × 3 × 7 × 17 = 714 2 × 3 × 7 × 19 = 798 2 × 3 × 7 × 23 = 966 2 × 3 × 11 × 13 = 858 2 × 3 × 11 × 17 = 1122 2 × 3 × 11 × 19 = 1254 2 × 3 × 11 × 23 = 1518 2 × 3 × 13 × 17 = 1326 2 × 3 × 13 × 19 = 1482 2 × 3 × 13 × 23 = 1794 2 × 3 × 17 × 19 = 1938 2 × 3 × 17 × 23 = 2346 2 × 3 × 19 × 23 = 2622 2 × 5 × 7 × 11 = 770 2 × 5 × 7 × 13 = 910 . . 5 × 17 × 19 × 23 = 37145 7 × 11 × 13 × 17 = 17017 7 × 11 × 13 × 19 = 19019 7 × 11 × 13 × 23 = 23023 7 × 11 × 17 × 19 = 24871 7 × 11 × 17 × 23 = 30107 7 × 11 × 19 × 23 = 33649 7 × 13 × 17 × 19 = 29393 7 × 13 × 17 × 23 = 35581 7 × 13 × 19 × 23 = 39767 7 × 17 × 19 × 23 = 52003 11 × 13 × 17 × 19 = 46189 11 × 13 × 17 × 23 = 55913 11 × 13 × 19 × 23 = 62491 11 × 17 × 19 × 23 = 81719 13 × 17 × 19 × 23 = 96577

Before I retired (approx 12 years ago) I regularly worked on a windows based intranet. I found the ADLDAP class a great tool. In fact the system admins used to ask me to create reports that they couldn't accesss via their Microsoft network tools. https://github.com/adldap/adLDAP